An inkjet head configured by bonding a channel forming substrate to a drive interconnect substrate is well known in the art. The two substrates are bonded together with adhesive while a gap is maintained between the top surface of the channel forming substrate and the bottom surface of the drive interconnect substrate. A drive circuit is disposed on the top surface of the drive interconnect substrate and a flexible printed circuit board is bonded to the drive interconnect substrate. The flexible printed circuit board is bonded to one longitudinal end of the drive interconnect substrate.
However, in the conventional inkjet head described above, the space formed between the channel forming substrate and the drive interconnect substrate extends beneath the area in which the flexible printed circuit board is bonded to the drive interconnect substrate. Consequently, the drive interconnect substrate is susceptible to breaking or bending and separating from the channel forming substrate during the process of pressing the flexible printed circuit board to the drive interconnect substrate to bond the flexible printed circuit board to the same.
In view of the foregoing, it is an object of the present disclosure to provide a composite substrate that comprises a first substrate and a second substrate arranged with a gap separating the two substrates from each other, and that is capable of reliably preventing the second substrate from breaking or from bending and separating from the first substrate when a flexible printed circuit board is pressed to the second substrate to be bonded to the same.